SAN FRANCISCO — Giants manager Tony Vitello has taken a much different path than the two biggest coaching stars in the Bay Area. Long before he became the coach of the Warriors, Steve Kerr played 15 years in the NBA. Kyle Shanahan’s path was paved by his dad, two-time Super Bowl champion Mike Shanahan, and he was an accomplished offensive coordinator before taking over the 49ers. Vitello on Wednesday will become the first to manage a Major League Baseball game with no prior professional experience, and Buster Posey believes he one day will be viewed in a similar light as the other big-time coaches in the Bay Area. That’s in part because of the way Vitello has prepared for this job, including the fact that he considers himself a fan of coaches. Vitello, the son of a high school coach, has gone out of his way over the years to meet successful coaches in other sports, and in recent months he got a chance to hang with both Kerr and Shanahan. The manager and some of his players went up to San Francisco after FanFest in San Jose in January to take in a Warriors game and then shoot around on a practice court. That was a memorable experience for...